Original Article

Ind. J. Tub., 7992, 59, 229

COMPUTED TOMOGRAPHY FEATURES OF TUBERCULOUS MEDIASTINAL LYMPHADENOPATHY . Anand Jaiswal1, S.P. Khanna2 and M.P.S. Menon3

(Original received on 9.4.91; Revised version received on 18.11.91; Accepted on 14.12.91) Summar. A Computed Tomographic study (CT scan) was carried out on 11 patients suffering from tuberculous mediastinal lymphadenopathy (TML) with special reference to nodal involvement, besides the pleural and parenchymal lesion. For comparison, retrospective CT scans of eleven patients each of sarcoidosis and bronchogenic carcinoma and six of lymphoma with mediastinal glands involvement were analysed on the same lines. The following CT features were found to distinguish TML from the other conditions: (1) Presence of multi-chambered or multiloculated nodes; (2) Presence of calcification; (3) Rim enhancement; (4) Hypodense areas; and (5) Intact fascial planes (or minimal loss of tissue cleavage.

Material and Methods

(a)

eleven cases of sarcoidosis who had been similarly examined and investigated (includ ing pulmonary function testing and peri pheral or mediastinal FNAC of gland), and

Introduction

(b)

eleven cases of bronchogenic carcinoma and six cases of lymphoma in whom diagnosis had been established by histological or cytological examination were also studied.

Tuberculous mediastinal lymphadenopathy (TML) presents very commonly as a diagnostic problem. Despite several means of diagnosis, including clues from history, clinical examination, Mantoux test, chest radiography, sputum examination and bronchoscopy, one may not be able to distinguish TML from lymphnode enlargement due to other causes. Often, biopsy, histopathplogy and culture of the gland tissue have to be done to reach the correct diagnosis. An attempt is made here to describe the distinguishing features of TML, using Computed Tomography (CT) as a non-invasive aid in diagnosis. 1

Eleven patients with confirmed tuberculous mediastinal lymphnode enlargement were included in this study. All were clinically examined; also, sputum smear and culture for M. tuberculosis, Mantoux test (ITU, PPD), chest Xray and hematological examination were carried out. Peripheral lymphnode biopsy and bronchoscopy, bronchial biopsy and aspirate examination were done, wherever possible. CT guided fine needle aspiration cytology (FNAC) of the mediastinal gland was done by 21-22 gauge chiba needle and the material was cytologically and bacteriologically examined (for acid fast bacilli), wherever possible. For the purpose of comparing the CT findings among the TML cases,

The above mentioned patients belonged to our unit in V.P. Chest Institute where they were investigated and the diagnosis was established. The CT comparison study was undertaken on a retrospective basis. Siemen Somatom DR-H body scanner with 512 X 512 matrix size, slice thickness of 8 mm and 4 sec. scanning time was used. Patients were given a bolus of iodinated contrast medium (Urgraffin 60%, 4 vials) intravenously, after a test

LRS Institute of TB and Allied Diseases, Mehrauli, New Delhi; 2New Delhi Municipal Committee Polyclinic, New Delhi; V.P. Chest Institute, Delhi Correspondence: Prof. M.P.S. Menon, Clinical Research Centre, V.P. Chest Institute, Delhi University, Delhi-110 007.

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dose. Contiguous scans, 10 mm apart were taken from thoracic inlet to diaphragm. Additional scans were obtained at planes of interest. The particular features studied were site, number, morphological features and enhancement pattern of the nodes. Parenchymal and pleural involvement was also looked into. Results

TML The patient population consisted of 6 males and 5 females, in the age range of 10 months to 55 years. Fever was the most common presenting symptom. Four patients had neck glands while one had a chest wall abscess. Family history of tuberculosis was present in 4 cases. Mantoux test was positive in all the cases except one; in this case, diagnosis was confirmed by isolation of AFB from mediastinal glands and clinical response to antituberculosis therapy. Enlarged lymphnodes were seen on chest X-ray in all. Pleural thickening was seen in 5 cases and 7 cases had parenchymal disease as well (usually fibrotic). Sputum for M. tuberculosis (3 consecutive specimens) was positive in only 2 cases. Bronchoscopy, done in 3 cases, revealed extrinsic bronchial compression, mucosal oedema and congestion. Bronchial biopsy and aspirate examinations were non-conclusive. A cytological/histological diagnosis was made either from a gland or the chest abscess wall biopsy (Appendix Table). Presence of epitheloid cells and giant cell was considered confirmatory of tuberculosis. All the 11 patients showed good response to antituberculosis therapy. The CT features revealed that the nodal involvement was almost always multiple, with right paratracheal glands being the most frequently involved. The following characteristic features were also noted (Tables 1, 2 and Fig. 1): - Presence of multi-chambered (multiloculated) nodes, - Presence of calcification, - Rim enhancement, - Hypodense areas, and - Intact fascia] planes. Sarcoidosis

There were 11 patients (10 male & 1 female) in

the age range of 35 to 53 years. Two patients had joint pains and another two skin lesions. Mantoux test and sputum for M. tuberculosis were negative in all. Four patients had reticulo-nodular parenchymal lesions in addition to mediastinal glands on chest X-ray. Pulmonary function test showed restrictive pattern in 7 cases and obstructive cum restrictive function in one case, while 3 patients had normal values. Histological/ cytological diagnosis of granulomatous lesion was made in all. The CT features of mediastinal glands showed multiple and bilateral hilar enlargement, preserved fascial planes (except in one case) but calcification in none. Multi-chambered appearance and rim enhancement were less frequent (3 and 2 cases respectively) while pleural thickening was seen in 2 cases. Lung parenchyma showed reticulonodular involvement in 4 cases. (Table 2, Fig. 2). Bronchogenic Carcinoma

CT Scan showed usually multiple hilar or paratracheal (right or left) nodal involvement. Loss of fascial plane was seen in a majority of cases (Fig.3) while calcification and rim enhancement were not observed at all. Multichambered appearance, hypodense areas, and pleural involvement (significant effusion in 5 and pleural thickening in one case) were occasionally met with (Table 2, Fig. 3). Lymphoma : (3 cases each of Hodgkin’s and Non Hodgkin’s Lymphoma). The following CT features of nodal involvement were noticed (Table 2, Fig. 4): (i) Glands were found in anterior mediastinum, usually singly and of large size, (ii) Loss of fascial plane was seen in most of the cases, (iii) Rim enhancement and multichambered appearance was uncommon while calcification was not seen at all, and (iv) Hypodense areas within the gland were also commonly observed. Discussion

CT scanning is the most sensitive and effective non-invasive method of demonstrating mediastinal glands and their likely aetiology.

C.T. FEATURES OF TUBERCULOUS LYMPIIADENOPATHY

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Table 1 CT features in tuberculous mediastinal lymph node enlargement

Table 2 Comparison of CT features in mediastinal glands enlargement due to various causes

Tuberculosis One or more groups of mediastinal glands may be enlarged, most commonly the right paratracheal group1’2. Reede et al3 studying CT patterns in tuberculous neck glands observed a frequent

presence of multi-chambered mass with a ring like area of enhancement. The fascial planes around the mass were normal. These features were also observed by us in mediastinal glands due to tuberculosis while calcification was also found in a significant proportion of our cases (7/11 cases).

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Fig.l CT features in TML: Upper thorax shows large paratracheal lymphnode with rim enhancement and hypodense areas in centre suggestive of caseation. The gland has multichambered appearance and tissue plane is well demarcated.

Fig. 2 CT features of mediastinal lymphadenopathy due to sarcoidosis: hilar and subcarinal lymphadenopathy. The gland does not show multichambered appearance and no hypodense area is seen. The fascial planes are intact.

Siegelman4 had noted that lymphnodes due to granulomatous infections have ill-defined margins but this was not seen in any of our cases. Sarcoidosis Such glands are usually multiple, bilaterally symmetrical and moderately enlarged, with well defined margins, i.e. with preserved fascial planes4. Both these features were present in our study as well. Calcification has also been described in sarcoid glands5, the frequency of calcification being related to the length of observation/duration of disease. Since most of our

Fig. 3 GT features in malignant (bronchogenic carcinoma) mediastinal glands: enlarged, bilateral hilar and posterior mediastinal glands. There are hypodense areas in glands. Loss o| tissue cleavage is well seen on the lateral borders of the large glands (on the right side). Rim enhancement and multichambered appearance is not seen.

Fig. 4 CT features in Lymphoma (mediastinal) glands: CT scan mid thorax shows large antimediastlnal lymph node mass with hypodense areas within. The loss of tissue cleavage (fascial plane) is also seen.

cases were in Stages I or II, calcification in the glands was not seen by us. To sum up, the pattern of distribution of lymphnodes, presence of calcification and multichambered morphology can distinguish the TML from sarcoid glands on CT. Other morphological features like rim enhancement and hypodense areas are less distinguishing. The associated reticulo-nodular pattern of parenchymal disease, if present, may be of additional help.

C.T. FEATURES OF TUBERCULOUS LYMPHADENOPATHY

Lymphoma

The frequency of intrathoracic lymphnode enlargement is 50 to 70% in Hodgkin’s disease6. The nodal involvement is usually bilateral and asymmetrical. On CT scan, glands are found in anterior mediastinum, large in size, with smooth or lobulated margins7’8 but no calcification in untreated cases9. The present study also showed large lymphoma glands usually in anterior mediastinum and without any calcification. Besides, the other distinguishing features from TML were the uncommon presence of multichambered appearance and rim enhancement and very frequent loss of fascial plane in lymphoma. Incidentally, the latter was the single most important feature to distinguish lymphoma from benign causes of mediastinal lymphadenopathy i.e. TML and sarcoidosis.

cleavage tissue plane, if seen on CT, should alert the physician to consider a malignant process and not TML. References 1. 2.

3.

4.

5.

Bronchogenic Carcinoma

The carcinoma glands did not show calcification or rim enhancement. Multichambered appearance was seen in only one case. The loss of fascial plane, as observed in lymphoma, was a common feature. From our study, we can conclude that hypodense areas within the glands, on CT scan, are not a diagnostic feature of tuberculous glands (TML) which tend to show matting and rim enhancement more frequently. Trabeculation (multichambered appearance) and calcification are also features which distinguish TML. Loss of

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9.

Kendig, E.L. Tuberculosis-Pulmonary Disorders. Philadelphia Saunders. 1972 pp 642-695. Lincon E.M., Sewell E.M. Tuberculosis in children. New York. Mc.graw Hill 1963, p 71110. Reede, D.L. and Bergeron, R.T. Cervical Tuberculous Adenitis: CT manifestations. Radiology; 1985, 154, 701. Siegelman, S.S., Zerhouni, E., Naidich, D.P. Tomography of the Thorax. Raven Press, New York 1984; p 43-81. Israel, H.L., Lenchner, G., Steiner, R.M. Late development of mediastinal calcification in sarcoidosis. Am. Rev. Resp. Dis.; 1981, 124, 302. Blank, N. and Castellino, RA. Mediastinal Lymphadenopathy. Semin. Roentgenol; 1977, 12 (3), 215. Moore, A.V., Korobkin, M. and Silverman, P.M. Computed Tomography of the Chest. Ed. Godwin JD. JB Lippincott Company. Philadelphia. 1984; p 207-240. Soloman, E.H., Haaga, J.R. Computed Tomography of the Whole Body. Vol. 1 Eds. Haaga J.R. and Alfidi R.J. The C.V. Mosby Company. St. Louis Toronto. 1983; p 430-492. Strickland, B. Intrathoracic Hodgkin’s disease. Br. J. Radiol; 1967, 40, 930.

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